// Copyright (c) 2010 libmv authors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

// Copyright (c) 2012, 2013 Pierre MOULON.

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include "conditioning.hpp"

namespace openMVG {

// HZ 4.4.4 pag.109
void PreconditionerFromPoints(const Mat &points, Mat3 *T) {
    Vec mean, variance;
    MeanAndVarianceAlongRows(points, &mean, &variance);

    double xfactor = sqrt(2.0 / variance(0));
    double yfactor = sqrt(2.0 / variance(1));

    // If variance is equal to 0.0 set scaling factor to identity.
    // -> Else it will provide nan value (because division by 0).
    if (variance(0) < 1e-8)
        xfactor = mean(0) = 1.0;
    if (variance(1) < 1e-8)
        yfactor = mean(1) = 1.0;

    *T << xfactor, 0, -xfactor * mean(0), 0, yfactor, -yfactor * mean(1), 0, 0, 1;
}

void PreconditionerFromPoints(int width, int height, Mat3 *T) {
    // Build the normalization matrix
    double dNorm = 1.0 / sqrt(static_cast<double>(width * height));

    (*T) = Mat3::Identity();
    (*T)(0, 0) = (*T)(1, 1) = dNorm;
    (*T)(0, 2) = -.5f * width * dNorm;
    (*T)(1, 2) = -.5 * height * dNorm;
}

void ApplyTransformationToPoints(const Mat &points, const Mat3 &T, Mat *transformed_points) {
    const Mat::Index n = points.cols();
    transformed_points->resize(2, n);
    for (Mat::Index i = 0; i < n; ++i) {
        Vec3 in, out;
        in << points(0, i), points(1, i), 1;
        out = T * in;
        (*transformed_points)(0, i) = out(0) / out(2);
        (*transformed_points)(1, i) = out(1) / out(2);
    }
}

void NormalizePoints(const Mat &points, Mat *normalized_points, Mat3 *T, int width, int height) {
    PreconditionerFromPoints(width, height, T);
    ApplyTransformationToPoints(points, *T, normalized_points);
}

void NormalizePoints(const Mat &points, Mat *normalized_points, Mat3 *T) {
    PreconditionerFromPoints(points, T);
    ApplyTransformationToPoints(points, *T, normalized_points);
}

// Denormalize the results. See HZ page 109.
void UnnormalizerT::Unnormalize(const Mat3 &T1, const Mat3 &T2, Mat3 *H) { *H = T2.transpose() * (*H) * T1; }

// Denormalize the results. See HZ page 109.
void UnnormalizerI::Unnormalize(const Mat3 &T1, const Mat3 &T2, Mat3 *H) { *H = T2.inverse() * (*H) * T1; }

} // namespace openMVG
